When multiple parties communicate amongst themselves, they need a way to determine what the subject of their communication is and determine who is communicating with whom. When communications take place via structured documents (e.g., forms, databases), these determinations are aided by using unique identifiers (UID) for various subjects within the structured documents. For example, a social security number, a student identification number, or an account number are commonly used to identify subjects in structured documents regarding persons. However, parties may use distinct UIDs from one another, reuse UIDs differently than other parties, or introduce clerical errors into the use of UIDs. The inconsistent use of UIDs between parties makes linking related documents kept by different parties challenging. Although standards for structured documents help identify related documents, as more parties become involved in a series of communications, the challenges in making links between those documents grows exponentially with inconsistent UID use. This challenge is especially prominent as communications branch and parties involved in the communications do not directly address one another, but increasingly rely on automated systems to process structured electronic documents that comprise the communications.